The structure of heat-treated sol-gel-made SiO 2 samples containing copper or iron in various amounts was studied using Raman spectroscopy and x-ray diffraction. The treatments were in air in the temperature range 200-800 • C. Copper and iron concentrations were in the range 7-55 wt%. It was found that in the samples containing copper, the metal is mainly dissolved in the SiO 2 network when the thermal treatment is at low temperatures. For higher annealing temperatures, first a copper silicate is formed and then most of the copper forms cupric oxide particles at temperatures of about 800 • C. In samples containing iron, the formation of particles with nanometric size of the g-Fe 2 O 3 (maghemite) phase is observed after annealing at 500 • C. At 800 • C the maghemite phase is transformed into the stable hematite (a-Fe 2 O 3 ) phase. Copyright

Lubricant bases for metalworking applications make extensive use of water-soluble additives to reduce friction and wear. In order to do such task, these additives must form a lubricating film that separates the contact surfaces thus imparting good surface finishes to the worked parts. This paper presents a study on the tribological performance of aqueous solutions of ammonium thiomolybdate and ammonium thiotungstate. Tests were carried out on a pin-on-disc tribometer for a steel-aluminum contact while keeping load, entrainment speed, sliding distance, temperature, and concentration of the additive constant to study the lubrication effect of these two salts. Chemical analysis of the wear track indicates the presence of an in-contact-formed solid film enriched with MoS 2 and WS that reduces friction markedly.

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New lanthanide complexes with 4,5-bis(diphenyl)phosphoranyl-1,2,3-triazolate (L(-)), LnL(3).nH(2)O (1-8) and LnL(3)(phen).nH(2)O (9-16) (Ln = La, Ce, Nd, Sm, Eu, Gd, Tb, Er), have been prepared and spectroscopically characterized. The structures of LnL(3).nH(2)O (Ln = La, Ce, Nd, Sm and Gd) were determined by X-ray crystallography. The metal centers exhibit a distorted trigonal dodecahedron coordination environment with two symmetrically O,O-bidentate ligands and one unsymmetrically O,N- ligand attached to the metal; two oxygen atoms from neighboring dimethyl sulfoxide (DMSO) molecules complete the coordination sphere. This unsymmetrical ligand coordination behavior was also identified in solution through (31)P{(1)H} NMR studies. Photoluminescence spectroscopy experiments in CH(2)Cl(2) for both types of complexes containing Eu(III) (6, 14) and Tb(III) (7, 15) exhibit strong characteristic red and green emission bands for Eu(III) and Tb(III), respectively. Furthermore, NdL(3) (phen).5H (2)O (11) displays emission in the near-infrared spectral region ((4)F(3/2) --> (4)F(9/2) at 872 nm and (4)F(3/2) --> (4)F(11/2) at 1073 nm). The complexes containing 1,10-phenantroline exhibit higher quantum yields upon excitation at 267 nm, indicating that this auxiliary ligand promotes the luminescence of the complexes; however, luminescence lifetimes (tau) in this case are shorter than those of the LnL(3).nH(2)O series.